Bearing device and fan apparatus

ABSTRACT

In a bearing device equipped with a fastening element for rotatably supporting a drive shaft of a hand tool unit, the fastening element has a heat conducting structure for conveying heat from a bearing region of the fastening element into a ventilation region of said bearing element, and in a fan apparatus provided with a fan impeller for cooling a drive unit of a machine tool the fan impeller is provided to cool a heat conducting structure which conveys heat from a bearing region of the hand machine tool into a ventilation region of the same.

BACKGROUND OF THE INVENTION

The present invention relates to a bearing device and also to a fanapparatus.

A bearing device equipped with a fastening element for rotatablysupporting a drive shaft of a hand tool unit is known in the art. Thefastening element is frequently provided to hold a ball bearing in whichthe drive shaft is supported. Also, a fan apparatus equipped with a fanimpeller is known in the art. The fan apparatus with the fan impeller isfrequently provided for cooling a drive unit of a hand machine tool.

It is believed that the above-mentioned existing devices can beimproved.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide abearing device of the above mentioned general type and also a fanapparatus of the above mentioned general type, which are furtherimprovements of the existing constructions.

In keeping with these objects and with others which will become apparenthereinafter, one feature of the present invention resides, brieflystated, in a bearing device with a fastening element for rotatablysupporting a drive shaft of a hand tool unit, wherein the fasteningelement has heat conducting means for conveying heat from a bearingregion of the fastening element into a ventilation region of thefastening element.

This makes it advantageously possible to prevent the fastening elementfrom overheating in the bearing region. It is thus advantageouslypossible to prevent the occurrence of damage, for example to seals orball bearings, due to an overheating of the bearing region. Furthermorea favorable thermal contact between the bearing region and theventilation region is possible, without it being necessary fordust-laden air to penetrate into the bearing region. This advantageouslyprevents an increased wear due to a dust-induced contamination of thebearing region.

Hereinafter, the term “provided” is understood in this context to alsomean “designed” and “equipped”. In principle, the design according tothe present invention can be used in all bearings deemed appropriate bythose skilled in the art. But it can be used to particular advantage inhand machine tools due to the typically high dust loads to which theyare subjected and in particular, in hammer drills or percussion drillingmachines, due to the high mechanical loads to which the bearing devicesare subjected.

In another embodiment of the present invention, the heat conductingmeans are designed so that air circulates around them, at least in aventilation region. This makes it possible to achieve a particularlyeffective removal of heat from the heat conducting means.

According to another embodiment, the heat conducting means include atleast one metallic subregion. The typically high thermal conductioncoefficient and high stability of metallic substances permit theachievement of a particularly robust and effective heat removal.

A particularly space-saving integration of the heat conducting meansinto the hand tool unit can be achieved if a rotation axis of the driveshaft constitutes a symmetry axis of at least one subregion of the heatconducting means.

An inexpensive design of the heat conducting means can be achieved ifthe heat conducting means has a cylindrical subregion, which, in aparticularly advantageous embodiment, can be designed to encompass thedrive shaft.

A favorable thermal contact and advantageous dust protection can beachieved if the heat conducting means are designed to constitute a partof a labyrinth fan.

If the bearing device has at least one clamping element designed toclamp the fastening means to a housing, then it is possible to achieve aparticularly rapid, inexpensive assembly.

It is possible to eliminate the provision of additional tolerancecompensation devices if the clamping element is provided to assure atolerance compensation.

In accordance with another object of the present invention, a fanapparatus equipped with a fan impeller for cooling a drive unit of ahand machine tool is provided, wherein the fan impeller is provided forcooling heat conducting means in order to convey heat from a bearingregion of the hand machine tool into a ventilation region. This makes itpossible to advantageously prevent an overheating of the bearing region.

An effective dust protection of the bearing region can be achieved ifthe fan apparatus includes a labyrinth fan.

The novel features which are considered as characteristic for thepresent invention are set forth in particular in the appended claims.The invention itself, however, both as to its construction and itsmethod of operation, together with additional objects and advantagesthereof, will be best understood from the following description ofspecific embodiments when read in connection with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a section through a hammer drill with a bearing device anda fastening element for supporting a drive shaft,

FIG. 2 shows a section along the line II-II in FIG. 1,

FIG. 3 shows the fastening element from FIGS. 1 and 2,

FIG. 4 is a top view of the fastening element from FIG. 3,

FIG. 5 shows a drive unit with a fan apparatus, the fastening element,and the drive shaft,

FIG. 6 shows an alternative bearing device of a hammer drill, with aclamping element,

FIG. 7 the fastening element from FIG. 6,

FIG. 8 a part of a housing of a hammer drill, with a clamping element inanother embodiment of the present invention,

FIG. 9 is a sectional view of a hammer drill with a bearing device and afastening element for supporting a drive shaft in another embodiment ofthe present invention,

FIG. 10 is a top view of the fastening element and a motor housing fromFIG. 9,

FIG. 11 is a sectional view of the fastening element from FIGS. 9 and10,

FIG. 12 shows a flexible tolerance compensation element in anotherembodiment of the present invention,

FIG. 13 shows a flexible tolerance compensation element in anotherembodiment of the present invention, and

FIG. 14 shows a wedge-shaped tolerance compensation element in anotherembodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a bearing device equipped with a fastening element 10 forrotatably supporting a drive shaft 12, which belongs to a hand tool unitembodied in the form of a hammer drill and is attached to an armature ofa drive unit 28 embodied in the form of an electric motor. A first bevelgear 30 is press-fitted onto the drive shaft 12 and engages with asecond bevel gear 32 attached to a transmission shaft 34. The bevelgears 30, 32 transmit a rotating motion of the drive shaft 12 to thetransmission shaft 34, which in turn drives a hammer mechanism and arotating drive of the hammer drill to which the bearing apparatusbelongs.

The fastening element 10 is embodied in the form of a fastening plateand has a subregion 18 that is metallic, cylindrical, and represents aventilation region 18 of the fastening element 10. The fastening element10 and in particular the subregion 18 assumes the function of heatconducting means 14 that extend between the bearing region 16 of thefastening means 10 and the ventilation region 18. The bearing region 16is an annular region encompassing a round opening of the fasteningelement 10 that is in turn encompassed by the ventilation region 18. Thebearing region 16 is provided to hold a ball bearing 36 of the bearingdevice, which ball bearing can be subjected to intense heat duringoperation of the hammer drill. The heat absorbed in the bearing region16 is conducted by means of the metal of the fastening element 10 to theventilation region 18 during operation, from whence the heat can radiatefrom an inner surface and an outer surface. The opening is provided toallow the drive shaft 12 to pass through, whose rotation axisconstitutes a symmetry axis of the cylindrical subregion 18.

A fan apparatus with a fan impeller 26 for cooling the drive unit 28 ofthe hand machine tool embodied in the form of a hammer drill is alsoprovided to continuously circulate air around the ventilation region 18of the fastening element 10 and the heat conducting means 14 duringoperation in order to assure an improved removal of heat. To that end,on a back side oriented toward the fastening element 10, the fanimpeller 26 has a labyrinth fan 20, which is partially formed onto thefan impeller 26 and includes two cylindrical baffles encompassing thesymmetry axis of the drive shaft 12 and one sleeve.

The cylindrical sleeve, which is integral to the fan impeller 26, isprovided for sliding the fan impeller 26 onto the drive shaft 12, whichrests against an inner surface of the sleeve while an outer surface ofthe sleeve constitutes an inner wall of the labyrinth fan 20. Theventilation region 18 protrudes into an intermediate space between theouter surface of the sleeve of the fan impeller 26 and a first baffle ofthe labyrinth fan 20. A baffle formed onto the housing 24 of the hammerdrill protrudes into the annular intermediate space between the firstand second baffle of the labyrinth fan 20. During operation, air mustflow along a meandering path in the radial direction between the bafflesto the ventilation region 18, which prevents dust particles frompenetrating into the vicinity of the ventilation region 18. Duringoperation, the fan impeller 26 rotates and generates an airflow thatflows quickly past the surfaces of the ventilation region 18, thuscirculating around the ventilation region 18; the fan impeller 26 isprovided to cool the heat conducting means 14, which are designed toremove heat from the bearing region 16.

The sectional view depicted in FIG. 2 clearly shows how the fasteningelement 10 is attached to the housing 24 of the hammer drill. For thispurpose, the fastening element 10 has two hook-shaped tabs 38, 38′ onopposite sides, which engage with a clamping element 22 that is equippedwith corresponding hook elements and is embodied as a strip spring part.The clamping element 22 embraces a part of the plastic housing 24, whichin turn encompasses the transmission shaft 34. When mounted in place,the clamping element 22 clamps the fastening element 10 and with it, theball bearing 36, the drive shaft 12, and the fan impeller 26 to thehousing 24 in the axial direction in relation to the rotation axis ofthe drive shaft 12. The hook elements of the clamping element 22 areintegral to it, are formed out of a strip spring, and have a curvatureradius of approximately 3 mm, which permits an elastic deformation ofthe clamping element 22, thus assuring a tolerance compensation betweenthe housing 24 and the fastening element 10.

During an assembly process, first the fan impeller 26, then thefastening element 10, then the ball bearing 36, and finally the bevelgear 30 are slid onto the drive shaft 12 (FIG. 5). The assembled unitthus produced is then clamped to the housing 24 by means of the clampingelement 22.

FIGS. 6-14 show details or components of additional embodiments of thepresent invention. The description will essentially concentrate ondifferences in relation to the exemplary embodiment depicted in FIGS.1-5. With regard to characteristics that remain the same, reference ishereby made to the description regarding FIGS. 1-5. Characteristics andcomponents that essentially function in the same manner have beenprovided with the same reference numerals.

In the exemplary embodiment depicted in FIGS. 6-8, the tabs 38, 38′ of afastening element 10 have threaded holes provided to accommodate screws40, 40′ that attach the fastening element 10 to a housing 24. Thehousing 24 encompasses a hammering mechanism, is composed of multipleparts, and has an upper shell 42 and a lower shell 44. A clampingelement 46 embraces the upper shell 44, to which it is attached by meansof a screw 52, and engages in ribs in the lower shell 42 (FIG. 8).

In the exemplary embodiment shown in FIGS. 9-11, tabs 38, 38′ of afastening part 10 are elongated in comparison to the preceding exemplaryembodiments. As a result, the fastening part 10 is suitable for diagonalplacement inside a cross-section of a housing 24 in the shape of arounded square (FIG. 10). In an assembly process, the housing 24 isscrewed to a motor housing 48. In this assembly process, the tabs 38,38′ of the fastening element 10 are clamped between the housing 24 andthe motor housing 48 and are subjected to a slight bending stress fortolerance compensation purposes.

FIGS. 11-14 show other U-shaped tolerance compensation elements 50-50″,which are designed to be positioned between a fastening part 10 and ahousing 24. The tolerance compensation elements 50, 50′ each have springelements on the legs of their U-shape, which in the tolerancecompensation element 50 (FIG. 12), are embodied in the form of elongatedtabs that protrude from the legs at an angle and in the tolerancecompensation element 50′ (FIG. 13), are embodied in the form of camberedsubregions. The tolerance compensation element 50″ (FIG. 14) haswedge-shaped legs provided for insertion between the fastening element10 and the housing 24. Tolerances can be compensated for throughadaptation of the insertion depth. In addition, it is possible for abearing device equipped with the tolerance compensation element 50″ tobe offset in the axial direction with a prestressing force, thuspermitting the elimination of play.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofconstructions differing from the types described above.

While the invention has been illustrated and described as embodied in abearing device and fan apparatus, it is not intended to be limited tothe details shown, since various modifications and structural changesmay be made without departing in any way from the spirit of the presentinvention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can, by applying current knowledge,readily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this invention.

1. A bearing device, comprising a fastening element for rotatablysupporting a drive shaft of a hand tool unit, said fastening elementhaving a bearing region and a ventilation region, said fastening elementhaving heat conducting means for conveying heat from said bearing regionof said fastening element into said ventilation region of said fasteningelement.
 2. A bearing device as defined in claim 1, wherein said heatconducting means are configured to permit air to circulate around saidheat conducting means at least in said ventilation region.
 3. A bearingdevice as defined in claim 1, wherein said heat conducting means have atleast one metallic subregion.
 4. A bearing device as defined in claim 1,wherein said at least one subregion of said heat conducting means has asymmetry axis which corresponds to a rotation axis of the drive shaft.5. A bearing device as defined in claim 1, wherein said heat conductingmeans have a cylindrical subregion.
 6. A bearing device as defined inclaim 1, wherein said heat conducting means are configured to form apart of a labyrinth fan.
 7. A bearing device as defined in claim 1; andfurther comprising a housing, and at least one clamping element forclamping said fastening element to said housing.
 8. A bearing device asdefined in claim 7, wherein said clamping element is configured toprovide a tolerance compensation.
 9. A fan apparatus, comprising a fanimpeller for cooling a drive unit of a hand machine tool having abearing region and a ventilation region, said fan impeller beingarranged to cool heat conducting means provided to convey heat from saidbearing region into said ventilation region.
 10. A fan apparatus asdefined in claim 9, wherein said fan impeller is provided with alabyrinth fan.